"There was not a step out of place, it was sheer and utter perfection what you just did there." Amanda Holden said they had blown fellow dance troupe Flawless "out of the water",

As the result was announced Ms Boyle, an unemployed church volunteer, congratulated them, saying: "The best people won", and wished them "all the best".

The 48-year-old is still on course to make more than £5 million from television, advertising and record deals.

Paul Potts, who won the first series of Britain’s Got Talent, in 2007, is reported to have made almost £5 million from the show and experts say Ms Boyle, 48, will surpass that.

Some of Britain’s biggest music stars are already lining up to work with her. Elaine Paige, Boyle’s hero, has hinted at possibly singing a duet with her, while Andrew Lloyd Webber has also discussed a collaboration.

There is even speculation that Ms Boyle could land a role in a major West End show.

Music industry insiders, however, say her first priority will be an album of songs for Syco, the record label owned by Simon Cowell, the producer of Britain’s Got Talent and one of the show’s three judges.

Monday’s semi-final became the most-watched episode in the current series with 15.4million viewers, and it is thought the final was watched by as many as 20million people.